Acid and Bases in everyday life

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Definitions and Terms

• Acid
  • A substance which in solution produces Hydrogen ions or, more strictly Hydronium ions
    • $H^{+} or H_{3}O^{+} ions$
• Base
  • A substance which either contains oxide or hydroxide ion or which in solution produces the hydroxide produces the hydroxide ion
    • $O^{2-} \ or \ OH^{-} ions \ determine \ how \ basic \ it \ is$
  • A soluble base is called an alkali
• Indicator
  • A substance (usually a vegetable dye) that in solution changes colour depending on whether the solution is acidic or alkaline.
• Neutralisation
  • Reaction of an acid with a base
• Salt
  • Ionic compound formed when a base (alkali) reacts with an acid
• Acidic Oxide
  • An oxide that
    • Reacts with water to form an acid
    • Reacts with bases to form salts (or does both)
• Basic Oxide
  • An oxide that
    • Reacts with acids to form
    • But does not react with alkali solutions (such as NaOH or KOH)
• Le Chatelier's Principle
  • If a system at equilibrium is disturbed , the system adjusts itself so as to minimise the disturbance.
• Photochemical Smog
• Acid Rain
  • Rain that has a higher hydrogen ion concentration than normal
    • $Higher \ than \ about \ 10^{-5} mol L^{-1}$
• Molar Volume
  • The volume of one mole (in the back, on your datasheet)
    $0^{\degree}C \ and \ 100.0 kPa \Rightarrow 22.71L \\ 25^{\degree}C \ and \ 100.0 kPa \Rightarrow 24.79L$
• Ionisation Reaction
  • Reaction where ions are created
• pH
  • As the negative of base 10 logarithm of the hydrogen ion concentration
    • $pH=-log_{10}[H^{+}]$
  • Note: A change in pH of one unit corresponds to a tenfold change in Hydronium ions
• Neutral Solution
  • A solution in which the concentration of hydrogen ions and hydroxide ions are equal
• Degree of Ionisation
  • Fraction of molecules that has ionised!
• Concentrated Solution
  • Total concentration of solute is high (say -- above 5 mol/L)
• Dilute Solution
  • Total concentration of solute is low (say -- lower 2 mol/L)

Acid and Bases

Acids

• Properties of Acids
  • Sour taste
  • Sting or Burn the skin
  • (in solution) conduct electricity
  • Turn blue litmus red
  • React with active metals to produce a salt + hydrogen gas
    $Zn + 2HCl \rightarrow ZnCl_{2} + H_{2}$
  • React with carbonates to produce a salt + water + carbon dioxide gas
    $MgCO_{3} + H_{2}SO_{4} \rightarrow MgSO_{4} + H_{2}O + CO_{2}$
  • React with bases to produce a salt + water
    $NaOH + HNO_{3} \rightarrow NaNO_{3} + H_{2}O$
• Common Acids
  $HCl \Rightarrow Hydrochloric \ Acid, \ STRONG \\ H_{2}SO_{4} \Rightarrow Sulphuric \ Acid, \ STRONG \\ HNO_{3} \Rightarrow Nitric \ Acid, \ STRONG \\ CH_{3}COOH \Rightarrow Acetic \ Acid, \ (Vinegar/Ethanoic \ Acid) \ WEAK \\$

Bases

• Properties of Bases
  • Soapy/Slippery feel
  • Bitter taste
  • (in solution) good conductor of electricity
  • Turn red litmus blue
  • React with acids to produce salt + water
    $Ca(OH)_{2} + 2HNO_{3} \rightarrow Ca(NO_{3})_{2} + 2H_{2}O$
• Common Bases
  $NaOH \Rightarrow Sodium \ Hydroxide, STRONG \\ Ca(OH)_{2} \Rightarrow Calcium \ Hydroxide, STRONG \\ NH_{4}OH \Rightarrow Ammonium Hydroxide, STRONG$

Indicators

Common Indicators (Note pH colour change range for Methyl Orange/Phenophthalein/Bromothymol blue)